Question: A hovercraft takes off from a platform. Its height (in meters), $x$ seconds after takeoff, is modeled by: $h(x)=-3(x-3)^2+108$ What is the height of the hovercraft at the time of takeoff?
Explanation: The height of the hovercraft at the time of takeoff is given by $h(0)$. $\begin{aligned} h( 0)&=-3( 0-3)^2+108 \\\\ &=-3(9)+108 \\\\ &=81 \end{aligned}$ In conclusion, the height of the hovercraft at the time of takeoff is $81$ meters.